How to make my Ally devil not get banished from me

[flappeercraft]

So I have a devil controlled by the Monstrous Thrall spell and mindraped. I force him to give me the Ally +4 Profane bonus to intelligence as I am a Wizard based arcane caster (Got Monstrous Thrall through arcane disciple feat). How can I make someone not forcibly Banish him from my body or similar?

[Venger]

So I have a devil controlled by the Monstrous Thrall spell and mindraped. I force him to give me the Ally +4 Profane bonus to intelligence as I am a Wizard based arcane caster (Got Monstrous Thrall through arcane disciple feat). How can I make someone not forcibly Banish him from my body or similar?

what exactly are you asking?

is this devil a fiend of possession living inside your body? are you using the possession variant rule? what kind of monster specifically did you dominate?

[flappeercraft]

what exactly are you asking?

is this devil a fiend of possession living inside your body? are you using the possession variant rule? what kind of monster specifically did you dominate?

Possesion variant rule and I dominated a Cornugon/Horned devil

[Necroticplague]

Dimensional Anchor it/yourself? If you can't leave the plane, you can't be Banished back to your native one.

[Kelb_Panthera]

I think the OP is looking for protection from exorcism rather than banishment. The best defense is concealment. Very little can detect your possessing minion even when he's actively boosting you; even less if he switches to the rider variant. They're deuces difficult to exorcise as well. Unless you're expecting something to target your minion directly, it's probably not worth worrying about most of the time.

BoVD has imprison possessor, which might help. That's the only thing that comes instantly to mind.