 Thus his legitimate children were all considered "de facto" (practically) Swedish princes and princesses through their mother and through Birger's own royal ancestry.In 1251, Rikissa was married to the heir of Norway, Haakon Haakonson (1232–1257), titular king of Norway and co-ruler along his father king Haakon IV of Norway.Haakon and Rikissa had one son, Sverre, who died young (1252–1261).