[@Vega7285] You could start off with one and bring the other in at a later point, if you'd find that easiest! I personally like the sound of both concepts, but yep, there's plenty of time for you to choose. We'll keep a spot reserved for you :)

As for the magic, hmmm... A detective archetype could have an ability that lets them track down enemies/analyse weaknesses, or something along those lines. Maybe something involving a bullseye lantern, a light that was commonly used in investigation? So your character could have one she uses for light based attacks. Whereas a thief could be based on a sneaky animal like a cat or a fox, could have the typical shadow powers, or could be ghost-like as a play on the term "phantom thief". (That and there's taking inspiration from [url=https://en.wikipedia.org/wiki/List_of_fictional_tricksters]tricksters in mythology and folklore[/url].)