Can Thomas talk/send images/send notions into your character's mind? yes, but if he does it without any warning, or asking- she's liable to react negatively. she's met richie haha
Can Thomas poke around in your character's head/explore beyond just communication? yes, but same as above, if she learns about it!
To what extent is it cool for Thomas to explore you dude's brainpan? wherever the wind takes you, bb.
What kind of stuff would be cool to Thomas to dig up, if he spends more time snooping in your character's head? anything and everything! you've seen the canon, so feel free to pick at whatever. if you want her current in game status at the time you want to dig, just let me know and i'll write that up for you.
What stuff do you NOT want Thomas digging up in your character's head? nothing, though things to do with scott, her mother, and the temple in general are going to upset her if confronted about before she's ready to discuss them.
Do you want to do any kind of bleed over thoughts/feelings/memories if Thomas is flipping his shit while mentally connected? YES. DO IT. i can't promise she will react to this well either, but omg yes. yes.
Contact? smoke signals
Anything else? ♥