what could be seen as the base capabilities of a thief of life ? I know that god tier powers are based around ones own interception, but what do you think a thief of life can do ( beside the whole stealing health thing ) I would love to hear your opinion

Look no further than Condy. She Steals Agency from others- As a Tyrant, she imposes her rules over Troll and Human Civilization, and as a Master Manipulator, she corrupts Jade and Jane, definitely limiting their will and agency for her purposes! She also experiments with herself to get access to all the Troll Psychic Powers, effectively Stealing the powers of her own Species, through knowledge of Biology. Condy can also extend people’s lifespans- Which could tie in to how Rogues also ‘distribute what they steal’, which would imply Thieves do that too, but only when it benefits them.

Meenah is similar, she is the one with the plan to make the Ghost Army, and she basically uses their lives as Bait, it’s through her idea that Vriska and Aranea steal the Ghosts’ Agencies in her behalf. Similarly, she Stole her Friends’ Lives by detonating the Tumor. There’s quite a lot to the Thief of Life.