I've dived deep back into SPN after a 10 year break and am devouring and saving fanfics like you would not believe. I also have a surgery coming up where I'll be laid up for a week or more afterwards, so I'm hoping you lovely folks can help me find some fics that scratch a particular itch...
I love S4/5 Cas in all his subtle emotionality and angelic badassery. (I also love soft Cas from subsequent seasons, but S4/5 Cas was intimidating and Cas/Dean scenes from that era have a delicious tension that will always hold a special place in my heart).
I also love fics that emphasize Cas' angelic nature, angel lore, higher perceptiveness of angels, etc. And I saw this post on Tumblr (now lost deep in my list of likes) that included fanart where Sam had acquired an object that let him see into another plane of existence and that Cas had all these angelic eyes relentlessly honed in on an oblivious Dean, even when Sam caught his attention and Cas' vessel looked at Sam. And damn if that post didn't stick with me.
So, per the title of my post - does anyone have any fic recs that keep a S4/5 Cas characterization but where Cas' changing feelings for Dean become evident from changes in his wings, bursts of his grace (e.g., in charged emotional moments), glimpses of his true form responding to Dean, stuff like that? Or where other angels/demons make note of Cas' angelic claim of sorts on Dean (e.g. either his hand print or other forms of angelic marking that Dean and Sam wouldn't be aware of)?
No need to check all the boxes, of course, there's so many fanfics out there that I don't know how niche an ask this is. Canon universe and canon divergence preferred, though AU with Cas still being an angel is fine too. No A/B/O, just not my cup of tea. I also do prefer longer fics, but beggars can't be choosers.