The story of Aviksita and Vaishalini is found in the Markandeya Purana. It is a story which proves that destiny cannot be altered by humans. Aviksita was the son of powerful king Karandhama.
King of Visaladesha proclaimed a swayamvara (bride chooses husband from a group of suitors) for his daughter Vaishalini and Aviksita attended it. A word got out that Vaishalini would choose Aviksita as her husband. The other princes attending the ceremony grew jealous and they imprisoned Aviksita. This resulted in the swayamvara ceremony getting canceled.
Karandhama arrived with his powerful army and freed his son Aviksita.
Vaishalini declared that she will only marry Aviksita.
But Aviksita refused to marry Vaishalini as he was defeated by the other princes. The words of his father and other wise men did not change his mind. He considered himself not worthy of marrying Vaishalini.
Vaishalini now took the vow that she would only marry Aviksita. She left her palace went to perform penance in forest to get him as her husband.
Year passed wife of Karandhama and mother of Aviksita, Veeradevi performed intense austerity named Kimichchaka. As per the rules of the austerity, the person was supposed to give whatever anyone asked. Veeradevi asked his son to give whatever anyone asked.
Aviksita distributed alms. Karandhama too came before him and asked for a grandson.
Aviksita now had to get married to give his father a grandchild.
Aviksita now took the wow that he will find out the whereabouts of Vaishalini and marry her.
During his search he heard the voice of woman – she was shouting – Please save me! I am the wife of Aviksita.
When Aviksita reached the place he saw a maiden being forcibly carried away by a demon.
Aviksita fought with the demon and killed him. Devas appeared in the sky and showered flowers on Aviksita and asked him to marry the woman. But Aviksita told the Devas that he will only marry Vaishalini.
Devas then told him that she is the same Vaishalini and she has been performing penance to get him as husband.
Thus Aviksita and Vaishalini got married and they had son named Marruta. In spite of the stubbornness of Aviksita destiny made him marry Vaishalini.