Harry Potter and the Goblet of Fire
Triwizard Tournament: Durmstrang Champion
We first see Viktor Krum when he's playing Seeker for the Bulgarian national Quidditch team at the Quidditch World Cup. Viktor has a scowling face and a thin, graceless body (while he's off a broom, at least), and Hermione isn't at all impressed – at first. But Ron is a huge fan: he's only about the best Seeker in the world! Even though Ireland wins the World Cup, Viktor still manages to catch the Snitch through some very impressive and determined flying (ha! – "Wonky-Faint" (19.26)). Ron desperately wants his autograph.
Then, Viktor comes to Hogwarts to become Durmstrang's champion for the Triwizard Tournament. Hermione starts noticing that Viktor is spending all of his time at the Hogwarts library. She finds it annoying because where Viktor goes, "groups of giggling girls" (19.25) follow soon after – hardly library behavior! Everyone is impressed by his international Quidditch fame, and tons of Hogwarts girls have crushes on him. Still, even if Viktor is regularly surrounded by lots of girls, he's only got eyes for one studious, bushy-haired fourteen-year-old: Hermione. He asks her to the Yule Ball, and later he tells her that he has "never felt the same way about anyone else" (27.33). Viktor also invites Hermione to come and see him in Bulgaria, and Hermione seems interested.
We like Viktor a lot, and not only because he makes Ron wild with jealousy (that kid really needs to start getting in touch with his feelings for Hermione). The bigger reason we like Viktor is that he seems down-to-earth, in spite of all his Quidditch fame. He appears genuinely into Hermione, in a quite adorable way: he asks her to coach him to say her name properly ("Herm-own-ninny" (23.103) – awwww!). He also takes Harry aside before the third task to ask "vot there is between [Harry] and Hermy-own-ninny" (28.153), thus treating Harry like a real rival even though Viktor is an eighteen-year-old international Quidditch star. He doesn't seem to think of himself as all that special, which we would have a hard time doing if we had played in the real-life World Cup. His crush on Hermione, a Muggle-born witch, also reveals that he lacks the bigoted nature of Voldemort's supporters.
There's some suspicion throughout the book about whether Viktor might be a Dark wizard. Being Karkaroff's student does his image no favors, and Mr. Crouch seems very suspicious of the kid when he stumbles out of the forest. Sirius scolds Harry, "what do you think you were playing at, walking off into the forest with Viktor Krum?" (29.92). And during the third task, Viktor casts the Cruciatus Curse on Cedric Diggory until Harry comes along and Stuns him. (It turns out later that Moody used the Imperius Curse on Viktor to make him do this. We thought that sounded rather out-of-character!)
But even though the novel keeps up some tension about Viktor's loyalties, by the end we know he's a decent guy who just has the misfortune of looking all dark and intense and being stuck at Durmstrang as Karkaroff's favorite. When the Tournament ends, Viktor makes a point of telling Harry, "I liked Diggory [...] He vos alvays polite to me. Alvays. Even though I vos from Durmstrang" (37.76). Viktor may look bad-tempered and awkward, but his heart is certainly in the right place. Even Ron seems to realize this by the end, when he finally asks for Viktor's autograph in spite of all his jealousy.