When Bond is asked if he has a preference in how Q wears his hair, he always answers “no.”  The man, surely, is allowed to wear his hair however he likes it, after all.

This would be a lie.  Bond has very specific preferences.

He absolutely hates it cropped short.  It’s how he prefers to wear his own hair, but on Q it makes him look almost haunted and disconcertingly unfamiliar.

He’s also not a huge fan of Q’s beard and shoulder-length hair.  It looks nice enough, and Q often gets compliments from others, but James finds it’s often in his way.

His favorite is the style Q wore his hair when they first met all those years ago: long and wavy or curly on top, trim around his ears and the nape of his neck.  Long on top is easy to justify: somehow, Q just doesn’t look like Q without the floppy fringe.  It took him a while to understand the rest of his preference, but decided in the end that he liked the little glimpse of Q’s long neck it offered… he liked spying that sliver of skin at odd moments in Q Branch.  Enjoyed watching it catch other agents’ eyes, watching them lick their lips, all the while knowing he himself would be the only one tasting that bit of skin.

So imagine his pleasure upon coming home after a short mission and discovering Q had shaved his beard and cut his hair, just so.  He toed off his shoes and padded into the kitchen, embracing Q from behind as he plated their dinner and kissing that sliver of newly exposed skin on the nape of Q’s neck.

“You could have just said, you know?”  Q smirked, tilting his head to give James better access.

“I knew you’d work it out,” James said as Q turned in his arms to kiss him properly.  “You’re very bright.”