I try not to go too complicated with mine, cause my style is simplistic on purpose because of how long I intend it to be (so that it's easier for me to draw everyone 10000x over) so the few characters with tattoo's or markings usually have them as really simple. (I forget them a lot too and usually have to go back and re-upload pages or characters with them drawn in, so I completely understand artists wanting to avoid that frustration)
The comic though isn't a romance focused, it's more of a plot driven, fantasy, slice of life, BL (as in... a story about someones life, not gag a days) with the romance indeed there but romance more slow burn.
Anyway, there's several characters with this or something similar on their necks or wrists.
Three characters with some variations of clock hands (the third character is not here but the tattoos are on her arms)
And then Osiris with his ostrich feathers.
(sorry for most of the examples being sketches and not comic panels, you're just able to see them clearly in the sketches)