Lyn did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Lyndis (リンディス Rindisu), also known as Lyn (リン Rin, Lin in the Japanese version), is one of the three main characters of Fire Emblem: Rekka no Ken, although she is not mentioned in Fire Emblem: Binding Blade. She is 18 years old in her story (15 in the Japanese version) and 19 (16 in the Japanese version) years old in Eliwood's or Hector's story.
She is one of the few female main characters in the series, the others being Celica, Eirika, Micaiah and Lucina.
From her humble origins in the plains, Lyn has been noted as a deep, caring, and kind-hearted soul. She rarely thinks ill of others and, despite the circumstances, always believes on the best of things. However, due to the slaughtering of the Lorca tribe due to the bloodthirsty Taliver Bandits, she has a great hatred toward all bandits and pirates and refuses to be associated with them unless needed to. In fact, the motivation for her travels was to become stronger and kill each and every Taliver Bandit in the mountains in order to avenge her parents. However, she does show mercy to any brigand or pirate that is not a Taliver Bandit, though does not hesitate to defend her friends from them nevertheless. Her serene nature (and the fact that the Saceans "never lie") has earned her the friendship and trust of many of her friends, and the affection of others, including fellow lords Eliwood and Hector, her knight Kent, or a fellow nomad, Rath. Though she seems innocent enough, she will kill anyone that attempt to kill or have killed any of her friends, showing her bravery and devotion toward revenge.
Super Smash Bros. Assemble
Lyndis appears in her Awakening attire in Super Smash Bros. Assemble, and unlike her last two appearances in the Smash Bros series, she is actually a playable character! Now armed with the Sol Katti, she is the fastest swordsperson in the game, at the cost of defense.
She also appears in the second E3 Trailer entitled "Tower of Smash". Robin and Ike attempt to break into the tower, with Ike grabbing a assist trophy that is cracked. Attempting to use it summons Lyndis, but something goes wrong as it shatters and Lyndis pops out in her Awakening attire. She slashes the door open and Robin, Lyndis and Ike enter.
Lyn in Fire Emblem: The Blazing Blade
Lyn in Fire Emblem Awakening
Lyn in Super Smash Bros. Brawl
Lyn in Fire Emblem Heroes (Portrait)
Lyn in Fire Emblem Heroes (Attack)
Lyn in Fire Emblem Heroes (Injured)
Lyn in Fire Emblem Heroes (Intro)
Bride Lyn in Fire Emblem Heroes (Portrait)
Lyn in Fire Emblem Warriors
Lyn hugs Kirby, because, They have the same Japanese voice actress