Powerful and flexible, Dexter gets my prizes for both most powerful and most potential for the 2026 core investigators. All of chapter one has shown us that five willpower and some spells to make use of it is already the makings of a top tier investigator. Combine that with the strongest signature card of the 2026 core and a fairly mild weakness (easy to deal with and won't even require an action on some board states) Dexter compares well to the top tier investigators from chapter one.
As a baseline his ability lets you play two assets at a time, which by itself is helpful to speed up setup. It may not trigger quite as much as someone like Joe, but it's going to give you some free actions every game regardless of what you do. It can start getting crazy if you add in assets with fast, or equivalent effects like Prestidigitation, which will let you "buy" actions on crucial turns.
The other part of the ability, to return an asset back to hand, is what really pushes his stock up and keep his deckbuilding and potential play patterns unique, fun and open ended. Being able to reset any asset means you can always reload a limited use asset if you need to, but it also means any card with an enter (or exit) play trigger gets very interesting. A unique effect like this is something you will always be able to revisit when new cards are added to the pool. I will really be on the look out for economy and draw effects attached to assets.