Is there a way to rename a follower?

From what I have found, you cannot do it via a console command. You will need a mod to rename a NPC.

You can download it from Skyrim Nexus.

Steps

1. Edit a NPC in Skyrim NPC Editor
2. Save to .esp file
3. Open TESsnip and open the .esp you just made
4. Double click EDID and click where the name is and type what you want
   for the name of the NPC
5. Now click on the Hex numbers to the left and put 00 at the end then
   click save at the bottom
6. Double click FULL and Repeat step 4-5
7. Now save your .esp as what you named your NPC example: Test.esp
8. Put the .esp in your Data folder in your skyrim directory then laumch the game
   and see your new renamed NPC

NOTE: When renaming a NPC make sure you scroll down
the list to see if their name is there then rename it to what you want
example: scroll down the list where EDID is and see if anyone of them has a name just look to the top right if its in mixed letters then dont edit it just the name if its there like in FULL and EDID