Only truly fluent language is English, but my family is Russian so I've grown up speaking that and can more or less get by in it. Additionally, I'm learning German at school and, although I'm not confident speaking it, I can understand spoken and written German with marginal trouble. As it turns out, watching Let's Plays as an unhealthy obsession is also one of the best ways to learn a language!
After exams end this year, I'll have a mountain of free time; I want to use that to start learning Japanese in a similar manner to German (get comfortable with the basics and then probably watch hours of Japanese Splatoon footage). The reason for that language specifically is that it's very relevant to my interests, if only Pokémon and Splatoon. In the long term, I'd ideally also get around to learning a Scandinavian tongue, A) because they look so silly and B) because it could be wonderful to move to Norway or Iceland one day.