Ruffnut Thorston

Ruffnut Thorston is a teenage inhabitant of Berk. She is the fraternal twin of Tuffnut Thorston. She is often arguing with her brother, often to the point of physical violence, though never seriously enough to separate them for too long. She is 14 years old in How To Train Your Dragon, 15 in the series, and 19 in the sequel.

Personality
In the first season of the TV series Ruff has a slightly more passive role than her brother, although she has a more prominent role in the second season. She's tomboyish in nature, mostly because she is a Viking, but she does tend to be slightly neater in terms of look and finds it offensive when Tuff negatively comments about her physique. Ruff is also seen to be extremely compassionate and selfless, as she was willing to cut her braids off in Free Scauldy so that they could serve as a substitute for rope without hesitation to save her friend. Ruff also stubbornly stood her ground when the gang tried to persuade her to leave when the Changewings were approaching, refusing to let Scauldy die. In the same episode, it's revealed that when they were little, while Tuff was afraid of the dark, Ruff was afraid of Tuff, although she outgrew this trait. While Tuff was talking with Barf about Ruff, he concludes out that she has a lot of rage and frustration because she feels trapped since she's "a woman in a man's world", as stated in Zippleback Down.

In the TV series, despite having tamed Barf (and technically Belch), she seemed to have a slight fear of wild dragons that could potentially kill her and would often panic in situations in which she encounters a wild dragon. In Free Scauldy, it's also shown that she might be afraid of dying, even to the point of naming the Scauldron "Please-Don't-Kill-Me" until realizing he was friendly. Also in the episode, she has a slight motherly side and is quick to comfort Scauldy like how often a mother treats her kids. Ruff loves punching and wrestling with Tuff, often proving herself stronger than him. Despite their quarreling, on occasion she is shown to pull herself and Tuff out of danger. Ruff dislikes having to share everything with her brother and had a brief fallout in Twinsanity, but they reconciled when they realized Barf and Belch were in danger. She also appears to be slightly more intelligent and serious than Tuff, explicitly shown in the episode Free Scauldy. In the movie, Ruff had a short-lived crush on Hiccup, but she seems to have dropped it because there is little evidence of Ruff having a crush on Hiccup during the TV series. However, in How to Train Your Dragon 2, Ruff has a crush on Eret. There is a possibility that, while neither of the twins score very highly on the intelligence side of things, Ruffnut is the smarter of the two, as demonstrated in episodes Frozen and The Eel Effect where she successfully pranked her brother.

Tuffnut
Ruffnut and Tuffnut have a strong love/hate sibling relationship. Although most of the time quarreling and fighting over trivial things in life, they show an inseparable bond with each other and rarely spend too much time apart. They both enjoy the feeling of pain, especially if the pain is inflicted on the other twin.

On occasion, Ruff is willing to help Tuff. In Zippleback Down, Ruff showed concern for her brother after realizing there was a forest fire approaching towards his location as well as when she saw a wild Typhoomerang (Torch) right next to her brother. She also was willing to stay up late to help Tuff out of the trap he got caught in (though it ended in failure). In the movie, Ruff is seen dragging her brother out of the Deadly Nadder's (Stormfly) blast of fire, in spite of their argument.

As twins, Ruff and Tuff share a strong invisible connection towards each other. They have the ability to understand each others thoughts and ideas without speaking, as shown several times to finish each others sentences or to have the same idea at the same time. They also have the ability to stay together as they are rarely too far apart for a long time. Wherever one twin goes, the other twin is never far behind, even if they intentionally try to stay away from each other. Ruff and Tuff also work incredibly well together (when they want to) and can synchronize themselves to do the same actions at the same time. It's also possible that they are able to sense where the other is and what happened to them, as other twins are able to do.

Barf and Belch
Being their dragon, the twins had to share riding it. The twins care tremendously about their dragon, although not as much as Hiccup. One head is loyal to each twin (Barf and Ruff, Belch and Tuff) and on occasion, the heads will fight each other when the twins fight each other. Usually the heads will work in unity if they feel that their riders are in danger and feel that their rider's constant quarreling is annoying. Both dragon and rider are willing to risk their necks to save each other. Tuff even states that Barf & Belch is his "totally awesome dragon" that he shares with his "totally un-awesome sister". Several times during the TV Series, Barf & Belch are seen to be extremely protective of their riders when they are in danger, as shown as they are willing to fight a Typhoomerang to defend Tuff in Zippleback Down as well as leaving the cave in The Night and the Fury to search for Ruff.

Hiccup Haddock
Not a lot of screen time is shown between the twins and Hiccup. Most of the time, they follow Hiccup's commands, although not always done in the right way. On occasion, they disobey him or misinterpret his orders. Despite Hiccup doubting their abilities most of the time, he acknowledges their abilities to work together if they want to. He gains respect for the twins when they figure out the idea to "fight fire with fire" in "Zippleback Down" and Tuffnut's ability to train Torch. Although finding them annoying from time-to-time, Hiccup is shown to care for them as he and the other Viking Teens attempt to find them after their disappearance in "View To A Skrill Part II" and was relieved to find out that Ruff and Tuff were both okay. He also acknowledges their decision to follow Alvin's ship to spy on him. They also care about Hiccup, (even though it's hard to tell), like when they, along with the other riders, were very happy to see that he was alive after the battle with the Red Death and when he fell down a hole, (then came out okay later), in Portrait of Hiccup as a Buff Young Man.

Astrid Hofferson
Although they rarely interact in the show or movie, they remain neutral to each other and will work together when it comes to it. Most times, Astrid will get angry if they do something wrong, especially if it's because they're not paying attention or just being silly. Like Hiccup, she doubts their abilities as Dragon Trainers due to their inability to pay attention, although it is assumed that she gained respect towards the twins when they put out the fire and trained Torch. On occasion, she will punch Tuff if he angers her, although Astrid is never shown on-screen to hit Ruff. It's assumed that Ruff and Astrid are on mutual friendly terms as they are the only girls in the group. Astrid was one of the Vikings who attempted to find the twins after they were blasted out of the sky in "A View to a Skrill Part II". It is presumed that off-screen, she had attempted to find them although Stormfly soon grew exhausted, showing that she does indeed care for the twins.

Snotlout Jorgenson
Snotlout and the twins share a close relationship. Often times, the twins will follow Snotlout and act as one of his supporters when he bullies Hiccup and possibly Fishlegs as well in the first film. In the game, they listen to Snotlout's plan to cheat in the competition against Hiccup/Astrid. Snotlout often thinks the twins are incredibly dumb and in return, they sometimes exclude Snotlout from their ideas, as seen in "Fright of Passage". Although sometimes siding with Snotlout, they occasionally bully him back, like how they fooled him into thinking he was dying in "The Flight Stuff". In View to a Skrill, it's presumed that Snotlout had attempted to find the twins (as stated by Hiccup) after they disappeared after being blasted out of the sky, which shows his apparent caring personality towards them.

In How to Train Your Dragon 2, Snotlout is shown to be flirting with Ruff, although she merely just grunts in annoyance.

Fishlegs Ingerman
Fishlegs and the twins rarely share any screen time together. Sometimes, the twins are seen to bully Fishlegs because of his size, although Fishlegs bests the twins in terms of knowledge. The twins find it annoying that Fishlegs knows a lot of things. In "A View to a Skrill Part II", Fishlegs attempted to find the twins after they were blasted out of the sky, along with Meatlug, but ends up over-exhausting his dragon. Even so, he offered to join Hiccup on his search again and shows worry when Hiccup tells him that there was no sign of them. Although being slightly annoyed at them at the start of the episode, Fishlegs compliments Ruff in Free Scauldy for her great work with the Scauldron.

In How to Train Your Dragon 2, Fishlegs is shown to be flirting with Ruff, although she merely just grunts in annoyance.

Stoick the Vast
Stoick is well aware that the twins are capable of causing dangerous accidents and pranks, as well as notorious for causing mischief. Ruff and Tuff show a level of respect for Stoick, possibly because he's the chief, but also like to make fun of him when he's not around. He's the one who possibly created the saying "Where there's smoke, there's the twins". In How to Train Your Dragon 2 along with the other riders, she searches for Hiccup being enforced by a worried Astrid, against Stoick's rule of no dragon flying while Drago is preparing for war. She also, along with the other dragon riders, Valka' and Eret, cries after Stoick's death as well as at his ship burial. She fires a flaming arrow to Stoick's sailing ship in honor of his chieftain legacy, and out of respect.

Eret
When the riders are rescuing Hiccup and Toothless, Eret shot a net at her and Tuff and she instantly fell for him as evidenced when she says (in slow motion) "Me likey." This is also shown when she is willing to become Eret's prisoner when she says (in slow motion as well) "Take me," while throwing her hands up in the air (while Tuff stares at her like she's crazy) followed by her and Barf getting caught in Eret's net. On Drago Bludvist's ship, she gazes in awe of Eret's muscles as he sets Stormfly free from Drago's trap.