Aranwë is only ever mentioned indirectly as the father of Voronwë, so we have very little information from which to derive his dates. We can definitely place him in Nevrast before I 116 (because his son Voronwë was born there, and Turgon's people left that land in I 116). On that basis, he most likely originated in Aman, and accompanied Turgon into Nevrast when the Noldor returned to Middle-earth. Indeed, his son Voronwë apparently confirms this when he calls himself '...kin of those who passed the Grinding Ice' (Unfinished Tales Part One I, OF Tuor and His Coming to Gondolin). This is a somewhat oblique comment, but its most natural reading would probably be as a reference to his father Aranwë making the crossing of the Helcaraxë from Aman into Middle-earth.

The wife of Aranwë is never given a name, but it is known that she was a Grey-elf who belonged to the kin of Círdan the Shipwright. Círdan was lord of the coastland regions of the Falas, directly southward of Aranwë's old home in Nevrast, a fact that further reinforces the idea that Aranwë himself had a degree of noble blood.

Aranwë's son Voronwë introduced himself to Tuor with the words, 'I am Voronwë son of Aranwë of the House of Fingolfin.' (Unfinished Tales Part One I, Of Tuor and His Coming to Gondolin). On its face, we might naturally take this to mean to Aranwë was a descendant of Fingolfin's House. Fingolfin, however, had only three children (Fingon, Turgon and Aredhel) and their own children are largely accounted for, so there is little room to fit Aranwë into the House directly.

Turgon had a single daughter, Idril, and Aredhel had only one son, Maeglin, so if Aranwë literally belonged to the House of Fingolfin, he must have been a direct descendant of King Fingon (and apparently a close relation to Gil-galad). There are indeed some questions of canonicity when it comes to Fingon's children (see note 1 to the entry for Gil-galad), but nonetheless it is very difficult to make sense of Aranwë as Fingon's son or grandson.

Much more likely, and indeed probably unavoidable, would be an interpretation of Voronwë's words to suggest that Aranwë served or followed the House of Fingolfin, rather than literally belonging to the line of royal descent.

If further confirmation were needed that Aranwë settled in Gondolin, we have the fact that Christopher Tolkien lists him as an 'Elf of Gondolin' in his index to Unfinished Tales (though he does not explain the reasoning behind that comment).

Aranwë's son Voronwë discussed the Nirnaeth with Tuor on several occasions, but never mentioned his father in connection with the battle. If Aranwë had fallen there, we might expect Voronwë to have mentioned the fact. So, while hardly conclusive, this does seem to suggest that Aranwë lived on past the Nirnaeth.