[No he is not an alicorn. He’s a pegacorn. No earth pony blood]
 
Mockingbird  
Mockery, Mox, Kissy  
Parents: Songbird Serenade, Snap Crackle Fizzlepop Berry Twist, Sassy Saddles  
Half-Sister: Tenebrae Berry  
Voice: Slightly feminine and airy  
Special Talents: Pleasing Prince Anarchy, representing the House of Discord, erotic poetry
 
Mox is the chaotic and feminine son of Songbird, Cpt. Fizzle and Sassy Saddles.  
Unlike his sister Ten, Mox is not a budding socialite but has enough sense to somewhat navigate the Canterlot social scene. He prefers to spend time in Canterlot’s Cemetary with his friend Lily Elegy and recite his racy poetry to her as she’s very tolerant to his nonesense.  
When he’s not lying on coffins waxing lyrical lust he’s by Prince Anarchy’s side as his lover [Anarchy refers to him as his concubine] and his personal adviser/annoyance.