Tvastr IE traits?

Tvastr was the father of equine goddess Saranyu, mother of As^vins, Yama, Yami, S^ani and Manu; of three-headed Tris^iras; creator of Vr.ta.

Loki was father of Midgard Serpent (cf. Vrtra), of Hel (cf. Saranyu)

Greek Phorkys Clan included Medousa (cf. Saranyu); Geryon (cf. Tris^iras); Ekhidna and her daughter Hydra (cf. Vrtra); Orthros and Kerberos (cf. Fenrir); Pegasos (cf. Sleipnir)