Amica Endura

You have to open your heart to others because Transformers hate metaphors.

On both Cybertron and Caminus, an Amica Endura is a Transformer's long-term best friend. For a species that can live for millions of years, that sort of lasting friendship is a big deal. On both worlds it involves a formal ritual, baring your spark and inviting someone to "receive my light" before explaining why you value them.

A related-but-distinct concept is the Conjunx Endura, the equivalent of a spouse.

Fiction

2005 IDW continuity

While a Camien Amica can become a Conjunx, on Cybertron you have to rule out being someone's Conjunx before "opting" for Amica. Your Fierce Tears On Caminus, a Transformer had to get an Amica by ten megacycles or general shunning would follow, The Sensuous Frame and the Oath of Constancy was said to form an Amica Endura. It was possible to split up with an Amica Endura on Caminus, known as "Platonic Severance", but rejecting an Amica, even one taken out of desperation, represented failure, failing to do enough to make the relationship work. The Frail Gaze Outright questions regarding another's relationship were considered gauche to ask. slaughterhouse

Nautica and Firestar formed an Amica couple out of mutual desperation, though their relationship was strained. The Sensuous Frame Nightbeat questioned Nautica if she had a Conjunx Endura, any Amica Endurae, or if her homeworld of Caminus practiced any sort of elective kinship. The answers were "no", "yes", and "yes". slaughterhouse Later, Firestar suggested that her and Nautica end their friendship, but Nautica refused. Their relationship got a bit better. The Frail Gaze When facing certain death, Nautica decided to open her heart and admit how she felt to her closest friends. Gathering Velocity, Skids, Rung, Brainstorm, and Nightbeat together, she opened her spark casing and recited the Oath of Constancy, as everyone joined hands and accepted. At Close of Day

Aileron, another Camien, was about to describe Sterling as her Amica Endura to Optimus Prime when she stopped herself and went with the Cybertronian equivalent, "best friend", instead. Aphelion

Ask Vector Prime

Stealth Saber and Victory Bomber were Amica Endurae. Spacewarp's Log (1), 2015/10/27

Notes

• As far as "Conjunx Endura" is supposed to be Latin, it is wrought with errors. Amīca is a noun that means "(female) friend". Endūra exists in Medieval Latin and while it looks like it's supposed to mean "enduring", it means a specific kind of fast and is a noun. It comes from the Latin verb indūrāre, which means "to solidify" and of which the particle is indūrāns. Amica Indurans would be a grammatically correct alternative. Furthermore, the plural "Amica Endurae" also fails to make amica the plural amicae despite otherwise following Latin rules.