Adonibaal is the RP Canon version of The Architeuthian. They are both the same character, in a sense, but the RP version is very different from the one that was made for the mod and was originally on thew wiki. Here, I will attempt to catalog some of who and what Adonibaal is, but the full experience would be reading the RPs and Interludes themselves.
I have written a short story about Adonibaal, his Departure, and the Fall, which you can read here: https://docs.google.com/document/d/19b6jRdhAnnNt_Htf4uQTTMNSwe1s2M-dPeZN0hBwWTE/edit?usp=sharing Some details about Bayal and Adonibaal's early history are consistent with wiki material and characterization, but much of it is more applicable to RP Canon than Wiki Canon.
Adonibaal's Deep Guard are also a RP only creation. In Wiki Canon, the Architeuthian held a bit more influence and prevented Adonibaal from going back to rescue some of his people, which the Architeuthian saw as unworthy.
My current RP writing guide, with excerpts from character moments and the like, for my own reference: https://docs.google.com/document/d/18NCkQMmEsAQ9a92BF5glVkmv9GnFM3rg9JO1ztv4QDw/edit?usp=sharing