Finished a bit late, Huge Question

1) I can't believe I waited so long to play this game even though I owned it since release.

I feel like Wyll just came out of nowhere. The upper area where you find Karlach and then the burning in is the literal last inch of the Act 1 map I didn't explore. Apparently I should have met him in the Druid place, but I talked to literally everyone there and don't remember him at all. Not sure if it's just because of the path I took through the game or not, but basically I randomly found Karlach hiding from the Tyr paladins, and then randomly after that Wyll decides to join the party.

My one criticism of this game is how buggy it is, so I'm mostly just asking if this was just bad/weird writing for the characters or if I missed part of their story/quest line.

Just want to say again that he definitely was in the Grove where he apparently was supposed to be, training the kids. My friend said I should have seen him during the initial Goblin fight outside the Grove, but that was so many dozens and dozens of hours ago that I can't remember.

On a side note.. doing my second playthrough and going to recruit Minthara this time. I had no idea she was even a playable character until I had to Google what Minthara's Underwear was and why it was in my inventory lol