It's funny, because although James Potter knew almost too many red heads, none seemed to have the exact same shade of retina- burning auburn as Lily Evans'.
James had been looking, you see. He'd scoured the halls of Hogwarts during terms and patroled the streets of Manchester/London/Bristol/Everywhere over break. He'd met gingers with freckles and gingers with blue eyes and sunburnt gingers. He'd met tanned strawberry-blondes and strawberry-blondes with atrocious platinum highlights to try and disguise their natural copper tresses. He'd met awful, unnatural crimson haired girls with black eyebrows that gave them away. James Potter had seen just about every combination of hair colour, skin colour and eye colour (although it was the hair he was interested in) you can think of. And not once, not once, did he find a girl that lived up to the delicately fierce, in your face, gingerness that was Lily Evans' hair.
While his friends were unaware of James specifically seeking out girls with fiery hair, it didn't escape their notice that they only ever saw him with girls of a carmine disposition. They could have chalked it up to "James being James" – he'd once gone 3 weeks eating nothing but chocolate frogs and mashed potatoes (separately, thank god), just because he felt like it. It wasn't unusual for James to fixate on inane, seemingly unimportant, details. This obsession had gone on too long for that, though.
Sirius swore that the last time he saw James willingly spending time with any girl other than a red head was at the beginning of fourth year, just before they started seeing girls as girls. 2 and a half years was altogether too long, and the boys had their theories – "He really likes carrots" – "He's trying to find out if pumpkin juice enhances natural gingerness" – "He's doing a public service and giving them all extra suncream."
Remus was the only one who even came close to figuring out the real reason behind James' infatuation, and he really didn't think it was his place to tell the lads – at least not until James was really running out of time to make his move on the real thing.
Because that's what this was, right?
He was either giving up on the ginger he really wanted, or he was trying to get insider information on secret tips to woo red heads.
And James never was the type that gave up without a long-winded, overly dramatic, whole hearted fight.