As a Swain Main and long lover of the champ (first favourite champ 4-5 years baqck when I started) currently rocking a 65% win rate with him! (was 75% untill last night -.-)
From his behaviour and the way he talks to her, not to mention the animations they share and co-operate. It's clear that they have some sort of bond.
And Swain being a Warlock must have found that by fusing with Beatrice he would gain what ever power she has, for the pair to become one.
Now if you think about it Rakan+Xayah are Humanoids. Why isnt Beatrice? The argument here is simple:
- Swain is powerful enough to force her to be his pet draining her true form and forcing her to stay close to him or he kill her.
- Beatrice is also evil and a lover of war, happily shareing her power with swain and chose a small form to accompaney him more easily.
- Beatrice is litterally just a catalyst containing a power that would be dangerous for swain to always have in his blood.
- Basiclly 3 but he puts his true power into a small bird to "fit in" untill he needs them(as he has done this since being a teenager).
In all this it is possible that he is a half blood Human and Vastayans (The lolwiki now says this) he is a Warlock and Mostlikely can shape shift...that being said, maybe he is full Vast and can shape shift himself to look human (he wears human boots and has human hands) otherwise he may never reach the position as General in the Noxian army.(Although already condiered this by most). Being any ammount of Vast would explain the birds loyalty and initial interest...but my main veiw is she/it is a catalyst that he made. One that he has also grown fond of as a pet.
Side note:
His face has been discribed as being so numb and emotionless it has been concidered to be a mask. Although he could have a scaryily high pain threshhold (which makes perfect sence for a man so effective in the art of war) the puppet/mind control theory connot be completely debuncked just yet as a puppet would not feel pain at all or atleast, be able to display it.
Hope you enjoyed this as much as I did thinking about it and thank you for allowing my mind to concider all this :)