EzioAuditore_1
I'm a simple man, my options are quite standard, mainly because any of the following might probably be mentioned, and you choose the most convenient one to add, or more than one (I think Cao Cao can meet these people before Canon DxD): Rossweise (the valkyrie needs to escape from Odin and love), Kuroka, Valerie Tepes (another sacred relic for the team and Romania, perhaps a moment to buff the vampires?), Venelana (maybe it's impossible *Sad*), Roygun (extra clans would be interesting), Yasaka (quite an interesting idea considering Cao Cao is a true deviation from canon), Lavinia, Latia Astaroth, Akeno, Ingvild, Serafall, Suzaku Himejima, or Gabriel (I think this is already an ongoing option in this fanfic, so no need to mention it...) I think my type was quite exposed, and remember, THE MOST IMPORTANT thing, even if you don't add any of these or if another one wins, is the personality which I really liked about Scathach, so I trust how you'll handle it.
Gabriel = 16 + 1 Tiamat = 11 Grayfia = 9 (although this counts multiple comments likes so could be double ups, also the sanctity of marriage fellas 💀) Serafall = 8 (although this counts multiple comments likes) Realistically, I think Gabriel would be the least intrusive LI to write in aswell as being suprisingly ignored compared to the others on the list, so I'll have to agree there. Her background, the issue of becoming fallen and relation to the spear are all good plot points.