Merry Frans-mas @shorixarts! It seems I was your Secret Santa for this Fransmas, lol.
Admittedly most of my time making this was more just spent trying to figure out what to make at all that would fit being 'slowburn' like you wanted. Eventually went with a simple "Show the start and then romantic part of the relationship" I used your Ink-Stained AU, as one can tell. Not an intensely shaded work, but despite my attempts I couldn't find anything more detailed that really worked, and while I could keep trying, I think it would be out of the events intent to give it to you super late.
(PS: Don't even try to judge the mechanical accuracy of Sans's tool, that thing was made with like 2 reference images loosely being followed and like 87% Vibes. Lol)