This god  is credited with upholding rita, or the principle of natural order, in the Vedas, which regard him as the only good asura.
This god granted the infertile King Harishchandra a son and demanded human sacrifice in return. In one story, Bhrigu is  presided over as chief priest by this deity, who hands Arjuna the bow Gandiva after using it for one hundred years only to  have it thrown back at him after the Kurukshetra War's conclusion. One story says that swans transformed from being  black and white to just being white as a result of a blessing by this god, who assumes the guise of a swan to escape from  Ravana. This god, in return for assistance in fighting demons that were tormenting him, assists Rama's plan to build a  bridge to Lanka after being rudely summoned by the hero attacking his (*) domain with arrows and other weapons. This god  is credited with upholding rita, or the principle of natural order, in the Vedas, which regard him as the only good asura. This rider of Makara is often syncretized with Mitra. For 10 points, name this Hindu god who rules the celestial ocean.
This god granted the infertile King Harishchandra a son and demanded human sacrifice in return.
Varuna [or Baruna; or Waruna; accept Mitra until mentioned, I guess]