Hi priya,
Intercaste marriages have always been a problem in India. This custom is highly practiced in Southern and Western parts of country.
In your case, his family's negative image in their community and society might prove helpful to you. I really can't assure you, if it will. But somewhere, it might. Who would like to give his/her daughter to a family with a "negative" image in society? Ofcourse, there will be few difficulties as these things don't remain undercover for long. Also, both their children ran away to marry a person of their choice, clearly shows that parents are very adamant( even if they are not, but to others it may feel). This shows how dominating they must be. Had I been a father of a daughter, I should have given it a nice thought before giving my daughter in that family, ideally.
Situation right now is, that parents are emotionally weak and they can be requested to accept your match without giving much considerations to caste and community, etc. After all that has happened with them, they should open up their mind to new traditions, new mindset and modern outlook of society which is above this caste and community rudiments.
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