New player in a bad situation with demigods and portable holes

[texcurt]

Ok, so it was my 4th time ever playing and I already had re-rolled then leveled up. I'm playing a rock gnome warlock lol 5 and have taken the GOO pact. I had come into possession of a robe that had a dimensional hole with a 1 foot opening sewn into it. We had to travel to the plane of Shadows to negotiate a treaty with a dread lord to prevent them from launching an invasion of the prime realm. Long story short the demigod "shadow" GOO of the plane of Shadows shows up (my fault) and I manage to trap him while he is possessing a vampire dread lord in my dimensional pocket and defeat the dread lords guards and portal back. Needless to say the DM was not expecting this... so I'm weighing my options at this point. Can I broker a deal to release the GOO shadow back into the plane of Shadows and benefit as a warlock or should I expect him to lie to me and just consume my soul as soon as I release him? I'm not familiar with the shadow which is comprised of the souls of several great old ones. I guess it is mostly up to my DM, but I thought I would ask what you all think. Alternatively I could try to imprison him further in one of the subplanar rifts the shadow GOO himself created to imprison those he felt should be imprisoned within his shadowrealm...which could end equally as bad since he was the one who creates them.

[texcurt]

Also if I use my warlock spell to communicate to the shadow trapped in my dimensional hole can he lie to me or do they have to answer truthfully?

[TheCountAlucard]

Sounds kinda system-specific, there, bud. I didn't quite get the "GOO" meaning there. >.>

[Beneath]

GOO is probably Great Old One

So you have a shadow entity made up of several Great Old Ones bound in a magic hole in your clothes, 'cause you caught it possessing someone?

If they're anything like true to their origins in this campaign, you're doomed already. The logic of the Great Old Ones is not usually amenable to bargaining, and it's best not to have their notice.

[Hawkstar]

Seeing that the shadow beast is made of the souls of several Great Old Ones... Do the surviving ones see that creature as a threat, or ascension? You may have ended up the warden of this eldritch horror, a task now set upon you by your patron (Because while your patron may not care about the world or its inhabitants or anything non-GOO care about, it knows it does NOT want to end up with its own soul stuck in that mess).

There's nothing saying an extradimensional space, even one most people consider mundanely common, cannot be a fitting prison for an eldritch horror. Mages work with powers they only think they understand when dealing with time and space and dimensional shenanigans. Sometimes, though, their misunderstandings lead to an overall boon. Just... don't let anyone else get your cloak, or else the beast may escape again and wreak havoc on the world.

[Stealth Marmot]

Ok, so it was my 4th time ever playing...We had to travel to the plane of Shadows to negotiate a treaty with a dread lord to prevent them from launching an invasion of the prime realm.

Well...that escalated quickly. Do you mean this is the 4th game you have EVER played?