Character Analysis
In a family of pretty volatile folks, Uncle Eli seems to be the steady and reliable one. Unlike Nector, he wasn't known for his brains; he seemed a lot more interested in nature than books. Nector himself remarked that Eli had some pretty impressive non-academic talents that he couldn't match, despite being the anointed brainiac of the family: "Eli has second sense and an aim I cannot match" (3.1.1). According to Nector, Eli is also "shy and doesn't like to talk" (3.1.1).
When he got older, Eli seemed able to handle his liquor without going off the rails—and again, overall, he was about steady as they came:
Eli drank but he never lost his head. He rarely spoke. Sometimes we sat in a room all evening, hardly talking, although he spoke easy with the children. I'd overhear. He had a soft hushed voice, like he was stalking something very near. He showed them how to carve, how to listen for the proper birdcall, how to whistle on their own fingers like a flute. He taught June. (5.1.61)
That's right—despite being shy and never opting to get married or have biological children (although he was rumored to have been involved with Fleur Pillager at one point…), Eli was great with kids, and he was particularly close with June. In fact, he basically adopted her when she decided she didn't want to live with Marie and Nector any more. According to Albertine, Eli was "crazy about his little girl" (1.2.7). D'awwww.