Muggles' Guide to Harry Potter/Major Events/Viktor Krum

Overview
Viktor Krum arrives with the delegation from Durmstrang Institute to take part in the Triwizard Tournament. He becomes attracted to Hermione, making Ron jealous, though Ron does not realize this at the time. Though Viktor is quite clearly trying to take things to the next stage with Hermione, she gently rebuffs him, and they stay pen-pals until Ron and Hermione become a couple. Viktor then suggests, in Harry's hearing, that he would like to meet Ginny. Harry tells him that Ginny is going out with someone very big who gets angry easily.

Goblet of Fire
Viktor Krum arrives for the Triwizard Tournament as part of the delegation from Durmstrang Institute. He seems to be spending significant time in the library, something that irritates Hermione because of the gaggle of giggling girls that seems to follow him around.

At the Yule Ball, we discover that Hermione has been asked to the ball by Viktor Krum. Ron is quite upset by this, saying that Hermione is "consorting with the enemy".

In the Second Task of the Triwizard Tournament, the four Champions must each retrieve something valuable to them from the bottom of the lake. The thing that is valuable to Viktor is Hermione. Having rescued Hermione, Viktor is apparently having a fairly intense conversation with her on the shore. An article that appears in Witch Weekly shortly afterwards, written by Rita Skeeter, says that Krum has invited Hermione to spend the summer with him. Hermione admits that this is true, but wonders how Rita had found out.

Viktor takes Harry aside in late May and asks him if Hermione is his girlfriend. Harry is rather surprised by this, and says no. Viktor says that Hermione is always talking about Harry, and Harry insists that it is because they are friends.

We don't see much other interaction between Viktor and Hermione, but by this time it is pretty clear that Viktor is romantically interested in Hermione.

Order of the Phoenix
While Viktor Krum does not play any particular role in this book, we see that Hermione is writing a very long letter to him as Christmas holidays approach. Hermione says that he's just a pen-pal, but Ron comments that he would like to be a lot more than that.

Half-Blood Prince
Harry and Ron catch Ginny and Dean snogging in a corridor. In the ensuing quarrel, Ginny says that Harry has snogged Cho, Hermione has snogged Viktor, and Ron is simply jealous because he doesn't have anyone to snog.

Deathly Hallows
Viktor has been invited to Bill and Fleur's wedding. Hermione is taken aback to see him there. Harry, in disguise, stops to talk with him. Viktor is looking sourly at Ron and Hermione out on the dance floor. Seeing Ginny, he asks if Harry knows her. Harry replies that she is going out with somebody large and bad-tempered. Viktor angrily asks what is the point of being famous if all the best girls are already taken?

Notable Consequences
Krum's ongoing attempts to become more than a pen-pal to Hermione eventually result in Ron's committing himself. It is entirely possible that Ron would leave his relationship with Hermione languishing if Krum had not been trying to take Hermione for himself.

It is unknown whether Krum would have attended Bill and Fleur's wedding if Hermione was not likely to be present. It is certain that she seems more surprised that he will be attending than he is at finding her there. If Krum's appearance at the wedding is a consequence of this relationship, then so also are Harry's discoveries about the identity of Gregorovitch, and the use of the symbol of the Deathly Hallows as the mark of Grindelwald.

Analysis
There is no way of knowing exactly how much has been going on between Viktor and Hermione. True, Ginny does tell Ron that Hermione and Viktor have been snogging, but this is not conclusive, as Ginny at the time is mid-quarrel with Ron, and is trying to hurt him with words. It is entirely possible that Ginny is going from what is public knowledge and expanding on it for effect. It is certainly true, as we see later, that Viktor would like to spend time snogging with Hermione; what is not so certain is whether he actually has done so. Hermione, as we see here, has clearly set her sights on Ron early in the series, and it is uncertain whether she would choose to jeopardize her relationship with Ron by being known to be snogging with Viktor.

Greater Picture
Key to the enjoyment of any piece of fiction is belief in its characters; without believable characters, one simply does not care about the story. The author had plotted out this story to cover a span of nearly seven years, in the lives of characters starting the series at age 11. Knowing that her characters were going to go through adolescence, she also chose to write their relationships as an integral part of the story, rather than simply ignoring them in favour of the main quest, as is common in heroic fiction. As Viktor is an incidental figure and off stage for much of the series, of course, we cannot get much of a feel for his character's growth; in fact, his behaviour at Bill and Fleur's wedding would indicate that he has matured very little since we first met him, three years earlier. Krum still seems to evince the belief that he is irresistible to women on account of his fame as the Bulgarian national Quidditch team Seeker. While we cannot say this shows perceptiveness on the part of the author, as many sports professionals exhibit a similar behaviour, it is certainly true that the author has managed to write this character most convincingly.