[quote=@LokiLeo789]
Would it be possible for Amartía to make a Sin a Domain once he has made onr a Portfolio? Like Wrath for example, theres a plethora of Portfolios that could actually go with that if I could have it as a domain. Same with the other sins. 
[/quote]

It sounds (kinda?) reasonable to move a portfolio to a domain, but, man, Sin might not be the best option here if you're looking to claim a domain. It's tricky to define, and not very flexible, especially if you use the old Catholic deadly sins model, which is kind of arbitrary anyway. And in terms of writing, 'sin' as a power base needs a lot of care to avoid inflating divine actions with too much dark edgy content.

My own recommendation would be to focus on what Amartia actually does and wants to do. His themes, basically. Defining Chaos (Sin) as manipulating individualist and hedonistic desires of mortals, like what's happening in Xerxes currently, would be a good step towards working out what other portfolios of Chaos Amartia might want to go for. The deadly sins list is, again, a little out of place without a religious background, so the portfolios should function in their own ways and reasons instead.

For example, moving into Chaos (Wrath) is a nice move [i]because[/i] Amartia has had his fair share of angry/violent/passionately determined/vengeful moments and wrath-y powers might fit in to how he plans to use his army. The fact that wrath is in the deadly sin list doesn't really add anything, or even mean much, in the context of Amartia's goals and themes.

tl;dr look for portfolios in the way Amartia functions as a character, not by checking things off a list from an outside source.