I've avoided it for years now because I've started to expect being disappointed by Fate spinoffs, but I'm finally watching El-Melloi Case Files!! Read more for my Weird Part of The Night Thought Dump on this topic
I first saw Gray's design when she was added to the Japanese version of Fate Grand Order a long time ago. I remember logging in to get her, but I got really tired of the grind halfway through and settled for just checking out the fanart and wiki diving. It was cool that she was a sort of spooky grave keeper that solved mysteries! Her relation to Saber from Stay/Night seemed kinda contrived to create another Saber clone, but I do like Saber, and I empathized with the idea of "hiding your face in shame behind a hood".
I didn't think of her again until I was getting into Pathfinder 2E. At first I created a Champion that was the kind of character I wanted to make in every game as a sort of idealized version of myself. After playing for a while as my Champion, the Secrets of Magic playtest was released. I was looking to try doing something besides being a Paladin in everything I played, and the Magus class seemed like my kind of thing. I wasn't the only one though, 2 other players were also into the Magus, and I found myself reading over the Summoner's entry instead since I liked the idea of party variety.
The more I read on, the more I started to like the idea of playing a Summoner. I pieced together ideas, like the Eidolon being a violent spirit bound to their soul. I thought of Zappa from Guilty Gear, an otherwise normal guy who is possessed by a spirit that causes problems for everyone. I thought that it might be interesting to try to understand the spirit and work out why it was so angry as a sort of plot hook and a reason for my character to be traveling. She'd travel around seeking out the occult, solving mysteries and trying to ultimately solve her own.
And when it came time to imagine their appearance, my mind just sort of spit out Gray. I imagined they were similar, mainly the gray cloak and hood. I called her Ein, and soon the "gravekeeper" aesthetic was too powerful to ignore and I worked it into her character and...
...now I've played as Ein in 2 campaigns! And I'm just...really, weirdly attached to the design even though I know basically nothing about the character. Despite my best intentions not to play an idealized version of myself in a TTRPG, I think I accidentally made an even more powerful self-insert in Ein. Ein is closer to who I am, she has more of my insecurities and solves problems in a way I can understand more than simply "being a hero". I even found it therapeutic to play as her, like I was learning to bring out more of myself that could be confident and strong despite my ongoing struggle with self hate.
And maybe that's why I've not felt the need to actually watch Case Files despite using Gray as one of my avatars of choice online. But...that changes soon! I expect disappointment but I'll go in with an open mind!
anyway now I'm working on a Type Moon inspired TTRPG so I guess I'm just a fate nerd sorry