Petraleth

Petraleth is the non-binary ship between Petra and Byleth Eisner from the Fire Emblem fandom.

Canon
Byleth meets Petra at the officers academy at the monastery, if he picks the black eagles house, she will instantly be his student because she is part of the black eagles house. However if Byleth chooses the golden deer house or the blue lions house, then Byleth can still recruit her, before the 5 year time-skip. If Byleth is a female, then there would be no romantic tension between the two. However if Byleth is male, then, they can marry, before the final boss, if the player gets A level support with Petra, Byleth will vist his farthers grave and take out the ring that he gave him, his words will echo, of his farther telling him to give the ring to a girl that he loves as much as jearlt loved his wife, if the player chooses Petra, then after the final boss, they will get married.

Crimson Flower/Silver Snow
If the player/Byleth chooses the black eagles house, he/she will be introduced to Petra as one of his/her first students, if the player chooses to side with edelgard, Petra will support edelgard and Byleth in their decision to kill rhea and take over fodlan. If Byleth chooses to kill edelgard, then Petra will also support the players choice and will admit that what edelgard is doing, is very disrespectful and foul, she will assist and support Byleth in either route he chooses, she will also be available for marriage in either route.

Golden Deer/Blue Lions
If the player chooses the blue lions or golden deer house and does not recruit Petra before the time-skip, then Petra will become a enemy to Byleth, Claude or Dimitri. when she Fights Byleth, she will talk about how she desires peace and then tell Byleth that she must kill him in order to protect edelgard, when Byleth kills her, her regular death scene happens and she passes away. If the player recruited Petra, then she will go against edelgard and will join Byleth or Dimitri/Claude and will actively volunteer to kill edelgard. She also may or may not marry Byleth, depending on what choices the player makes throughout the game.

After the War
If Byleth chooses to marry Petra after the war, Byleth will talk to her at the goddess tower, Petra will talk about going back to bridgid, so that she can support her people and family and how much she will miss Byleth. Byleth will then offer her a ring, she will at first be shocked ,but Byleth will then confess his love for her and she will confess her love to him. The pair keep their marriage a secret until they come out and confirm that they will be married, Petra becomes the queen of fodlan, the two work together and eventually, bridgid and fodlan become one nation, thanks to their efforts. If the player does not marry Petra, then the two still keep close and as the emperor of fodlan, Byleth supports the people of bridgid and Petra.

Fanon
Despite not being a very popular ship, it’s gotten a bit of attention , only one fanfiction has been written as of now.

Moments

 * When Byleth becomes the progenitor god, Petra will note how Byleth looks very simalir to the nature dieties that she believes in.