Not him but how about not bench his character into nothingness because someone else filled the “have a crush on Marinette” spot nor flanderize his character to just “the gay artist”.
He got a sense of justice from his episode they could have explored. They could have even led him into an antagonist role by making him the antithesis of Lila: someone who gets akumatized on purpose not for selfish acts but to make justice which isn’t something the heroes like.
He starts losing hope in the heroes because how they don’t let him do justice which is when Hawkmoth enters, he managed to snatch 2 Miraculous, one for Lila and other for him to make justice so they would start working in a duo dynamic like a brother-sister.
They would know each other identities and work for Hawkmoth, Nathaniel won’t be informed of many things, Hawkmoth would just make Lila cause all the akumas and Nathaniel would support the enemies because he want to help them do their justice mission, while Lila just does it to defeat Ladybug. They would also help each other escape, Nathaniel does it because it’s the right thing and Lila does it because orders.
Also if you want to keep the whole “Love Triangle” shit, you can make him start gaining grudge to Adrien because his whole situation with Marinette.