My first siren oc:  
Marina Abyssmelody, a different siren dressing a age of sigmar armor.  
Short Story: She was a siren who did not agree to using the song to absorb the negative energy of others, which made her fight with her closest friends, the Dazzlings, except Sonata. In the end, taking the “Oceanic saber”, a sword that she found deep in the seas of Equestria, she run away from her kin. Without explaining it, she ended up in a portal that led her to the Mortal Realms, where she lived with the race known as Idoneth Deepkin, since then she covers her gem as a symbol of her determination.