John Lindow in his book, " Norse Mythology ", says this about Aegir : " The sea personified; a famous host to the Gods, but listed among the Jotnar. "
Wikipedia states that : "Ægir (Old Norse "sea" is a sea giant, god of the ocean, and king of the sea creatures in Norse mythology. He is also known for hosting elaborate parties for the gods. "
Aegir is hard to define. Very few Jotnar are allowed access to the Aesir as much as he is, and yet when Thor demands that Aegir brew the ale for the God's feast he becomes offended and tells them they must bring their own kettle. Unlike most Jotuns, however, he is allowed to sit with the Gods at their feasts, and in one of the Eddas, Aegir sits and speaks with Bragi as they discuss the history of the Aesir.
Aegir is married to the Goddess Ran and together they have nine daughters. ( The waves personified ) Ran, however, outside of Loki borrowing her net to capture Andvari, has little or no contact with the Aesir in the Eddas.
I have always seen Aegir as a friend of the Aesir and as a Jotun who by being accepted by the Gods was raised to Their level, much in the same way that Skadhi, and Gerd, were raised in stature. I like Aegir ! He is a jovial sort who likes to party, and who despite being a Jotun fits right in with the Gods.