her father had been for five years a serious enemy of king alfonso xi, his former protégé, and the king wished to neutralize or absorb the might of the peñafiel family. although juana was not the heiress (yet), already in her youth she had to go along with royal wishes. the king's very influential concubine, leonor de guzmán, wanted to obtain some high prestige and property to her eldest son and had her eyes on the young juana. on 27 july 1350 her brother and guardian, fernando manuel of peñafiel, had to marry his young sister to henry (1333–79), eldest of the illegitimate sons of alfonso xi of castile. this brought henry certain lands.