Last Name Agents:
Coulson - Only Phil to May
May - Only Melinda to coulson
Fitz - literally if you call him leopold there is something wrong with you
Hunter - Can't imagine calling him lance
Ward - barely counts and fuck him but whatever
Davis - does he even have a first name?
Sousa - will never be daniel, maybe danny
First Name Agents:
Daisy - Also Skye when she only had one name but who calls her johnson? no one
Bobbi - only agent morse in formality
Deke - technically not an agent but still
Lincoln - always lincoln
Both:
Jemma Simmons - Everyone switches between Jemma and Simmons
Nicknames:
Mack - Also known as Alphie, still a nickname
Yoyo- Too bad no one calls her Elena it's a very nice name but Yoyo is a great nickname
Tripp - Still Alive To Me and also i could never think of him as antoine
Unsure:
Enoch - I think that's his only name? And he's an alien so they likely have a different naming system anyway
Piper - Is that her first or last name? What's her full name? Who knows
