First line and first paragraph aren't bad, but they don't really hook me in either. Saying that 'it started' is too vague to grab my interest and the following lines introducing the character aren't spectacular either. You're telling us a lot about Tommy, but I'd much rather see that he's obsessed with books than be told about it.
"So that's it, pretty much my whole existence in a few paragraphs" and a boring existence at that, which makes the first few paragraphs boring too. That's not what you want in a first chapter, exposition about his early life, if you have to give it, should come later.
Right now the story needs a hook, be it action or something else, but it has to be interesting. The fact that when his father gave him his first book is also the last time anyone ever saw his father is an interesting thing, instead of portraying the rest of Tommy's life I'd focus more on this, right when you first mention "Run, Jump, Ride".
The small excerpt of the book Tommy's reading hooked me more than Tommy's storyline, at this point the story from the perspective of the huntsman and his wolves is better than that of the fourteen year old bookworm. We're three pages in and we know almost all there is to know about Tommy except why we should care. Yes, he lost his father, but that's barely a footnote, even to Tommy. Now I will say that though I've been reading first-person stories more than I used to I still like third person better, when I read first person I need to get to like the main perspective soon or I'm likely to put the book down. So maybe it's just me, but to me at this point Tommy is just not that sympathetic a character to read about.
On the fourth page the story changes when Tommy is sucked into the book, however this doesn’t immediately help make things better. Tommy’s life up to this point is very mundane, a normal house, normal school, normal everything. There isn’t a hint of magic and then suddenly he gets drawn into a book for no apparent reason. I wasn’t expecting magic and there is no lead in to tell the reader that it’s possible. Now we’re entering into the territory of the Earthling falling into a fantasy world trope, which isn’t a trope I like and have rarely seen executed well.
I hope you’ll prove me wrong.
Something that struck me about Tommy, in the form of Tamaska, is that he’s surprised by what he sees around him, but apparently not by the body he’s wearing. Instead of a fourteen year old boy he’s now a huntsman, he has a bow in his hands and an arrow notched, so he should see that his hands and arms are different now, more muscular or wiry or tanned, so are his clothes and everything else, but Tommy doesn’t notice these changes which I think is odd.
When Tommy thinks “hadn’t this guy ever heard of a washing machine” I really doubt Tommy’s intelligence and how much he’s actually read. He’s in the world portrayed in the book, Reule is a hunter who hunts together with wolves. There aren’t washing machines in this setting of warriors and battles!
Tamaska does have similarities to Thomas, but it made me pause before I remembered Tommy’s name is actually Thomas. Now I’m getting the picture that Tommy didn’t take over someone’s role in the book but was added as an extra, just the way he is. Even in furs he shouldn’t have the body of a hunter – he should stick out like a sore thumb. He notes that Reule is very dirty, but if he truly fits in with the book-world so is he, so when he sees his hands holding the bow he should also see filth. There’s a suspension of disbelief going on between Tommy and Reule that doesn’t feel natural. The way he looks, the way he can’t hunt, the way he threw up when Reule gutted the deer...but Reule doesn’t say a thing even though Tommy is the last person who should be hunting.
Back in the village Tamaska has a history in that world all of a sudden, including a wife. And though he knows something is off and that ‘Tamaska’ isn’t behaving as he should Reule covers for him. During the walk Reule also said nothing. I have the feeling he should have, when the role of ‘Tamaska the hunter’ is suddenly taken over by Tommy the bookworm, who is totally incapable of doing anything to save his life, there should be more of a reaction.
What I did like was Tommy’s reaction to the people in the book – this is showing me he despises being filthy rather than you telling me stuff, like at the start of the story. Especially the end with his wife was very well done, though Reule’s wink felt off – this is because I’m expecting him to worry about his friend’s odd behaviour rather than make light of it.