Oh boy. What will the insane young pink girl do to these helpless guys?
A note, human micros used in situations like this will never die by their specific captor WITH exceptions depending only on the situation like vore (these ones here won't die though). I'm not exactly a people person irl, but I also don't support them dying in unsuspecting ways, whether they be fictional or real. I won't ever draw them being squeezed to death or ripped apart, gored in any way, crushed into a bloodsplatter (cartoon comedy only) or fully seeing them be digested if they're swallowed alive (for that, it'll either just be sentient absorbtion where they're alive, but forever part of whatever body part they were absorbed into like breast for example where they're forced to always be groped and such).
The idea is they've been captured and will be forced to undergo who knows what if they want to either live or leave the captors presence. Alter egos Pinkamena and Fluttergoth are the only ones out of the Mane six that will sometimes quietly go against Twilight's orders and will do mostly lewd and weird stuff with them before taking them to Twilight. In Pinkamena's case, one will usually involve sending them inside of her mind where she created a very weird insane world inside just for them (I'm working on a power where Pinkie can send and trap people inside of her brain where the unknown crazy stuff will happen and only she can release them). In the case of say Tiara, Cozy, or Chrysalis they'll forever be slaves if the micros are caught and captured, but that's the bad thing. The good news is if Twilight and her friend's discover where they are or which wrongful type caught them before it gets to a point where they'll never be able to save them, they'll either plan a rescue mission to get them back or plead with whoever has them to obtain them. Most of them are already hiding somewhere in their house trying to escape sight. Some of the micros definitely won't mind being the slaves of their favorite captor though.
Forgot to mention, any other micros I use aside from humans or anthros will be their own little species. For example I drew purple micros in some of the Fluttergoth pics so I'll use those for the more extreme stuff only if I need or decide to.