"An ugly troll looked in through the window."
Translation:Ett fult troll tittade in genom fönstret.
"tittade in genom" That's the first I've seen "in" used in Swedish. When do you use in instead of i?
It's more like 'into' in meaning – it describes a direction "into" something.
Jag stoppade in brevet i kuvertet 'I put the letter into the envelope'
this results in
Brevet är i kuvertet 'The letter is in the envelope'
What's the difference between ''igenom'' and ''genom''? Is there a particular situation where one or the other can be used or is it synonymous?
genom has several other senses, but in the sense of going through something, they're interchangeable. :)