Lakshmin
The account of Sishupal being in Jarasandha's care was accurate, although not the part about him being an adopted son. If you recall, when Sishupal was born, he was born w/ 4 arms and 3 eyes - one on the forehead - and it was prophesied that those monster appendages would disappear once he's on the lap of the person destined to kill him. On an occasion that Krishna & Balaram visited his mother (who was their bua, like Kunti was), Krishna took the baby Sishupal in his lap, and those extra arms & eye disappeared. Srutadeva then begged Krishna to spare him, and Krishna promised to forgive him 100 times, which apparently Srutadeva took to mean forever 😆
Anyway, his father Damaghosha was worried, and decided that Sishupal would be safe from Krishna if he was put under the care of Jarasandha. He therefore sent him to be @ Jarasandha's service, and there he remained. Unwittingly, that also contributed to making him an enemy of Krishna, despite their relationship, and fulfilling that prophecy.
During the attempted marriage w/ Rukmini, he was still the yuvraj of Chedi, but was still being raised by Jarasandha. After Krishna's marriage to Rukmini, he harassed Krishna a lot of times, but was spared (in the process, burning up those pardons his mother had gotten for him).
Eventually, when his father died, he returned to Chedi and was crowned its ruler. Sometime after that, Krishna, Bhima & Arjun had that encounter w/ Jarasandha, which saw the end of him. When the Pandavas went on their Rajasuya conquests following that, Bhima entered Chedi, and Sishupal, recognizing where the power lay, welcomed him, and relations b/w Chedi and Indraprastha were not bad. Until Sishupala decided to insult Krishna in the Rajasuya yagna itself.
