very old pic of one of my favourite fountain pens, despite its temperamental issues, a platinum 3776 with a music nib
cheap kind of shitty steel nib shaped like shark: i'll write with anything. shimmer ink? baystate blue? iron gall? i don't give a Fuck 
beautiful gold-nibbed pen from a highly respected japanese manufacturer: what's that? a converter of waterman south sea? I'm allergic :( feed me platinum black cartridges only :(
and exaggeration maybe, but this is easily the least cooperative pen i own. it has some sort of air exchange struggle with converters that makes it run dry for no apparent reason; ten years of tinkering has not alleviated the issue. it makes up for it by being extraordinarily pleasant to write with when it receives an ink that doesn't make it throw a tantrum, by which i mean, proprietary carts only. i will probably experiment with syringe-filling empty carts with various inks to troubleshoot, now that i am thinking of it