What big part?
I missed him in my first PT and outside getting him as a camp vendor and seeing his canonically total incompetence, he doesn't do anything special.
It's not a huge part. But he is part of a quest, then joins your camp, and (Volo camp events spoiler)
is a method of attempted tadpole removal, with pretty significant effects to your PC
It's unclear what role he'll play in Acts 2 and 3, but it's not unreasonable to guess he'll be present throughout.
