I imagine this conversation taking place:

Dovahkiin: "Hey, Belrand?"
Belrand: "Yes, Dovahkiin?"
"Your hair is long..."
"Yes?"
"And rather scraggly and greasy"
"Hmph. Not my fault--there isn't one barber in the whole of Skyrim."
"And yet you shave your beard every. Single. Day. Seriously, you have a face like a baby."
"*grumbles* My beard doesn't look good long. It won't grow in even."
"Neither does your hair. You DO realize you're going bald on top, right?"
"I...I..." *flails at head* "Why didn't anyone tell me?? Blast Skyrim's lack of mirrors!!"
*hands Belrand a dagger* "Seriously, please cut your hair. Haven't you noticed mothers pulling their children inside when we pass by? You look a bit like a perve."
"*grumbles* "Alright, alright, I'll cut it."

As far as companions go, I've always liked Belrand's attitude as the goofy old guy, but I always thought his hair was completely gross. All the other changes to Belrand I could find on the nexus made him younger, and I've always felt that takes away some of his charm. So I simply changed Belrand's hairstyle. Nothing else. You're welcome.

This is my very first nexus upload, so please let me know if I configured anything wrong.

Compatibility: This should be compatible with anything that doesn't change how Belrand looks. I did run the file through TESedit and didn't find any problems.