In the Harry Potter series, Dumbledore seems to represent ultimate wisdom and authority. Harry (and the readers with him) hold him in awe; many times throughout the series Harry willingly accepts and follows Dumbledore's plans even when he doesn't understand them. Dumbledore is portrayed as trustworthy - so much that Harry grudgingly accepts Snape as an ally, against his own suspicions and based on Dumbledore's say-so, so much that Harry is willing to die when Dumbledore tells him he must.
I'm writing a character I'd like to share some of these aspects. Not quite to the same extent, but she's a mentor character who constantly withholds information but is trusted implicitly by my protagonist. It's important for me that this loyalty be considered genuine - I want readers seeing her as a source of support, not a potential backstabber.
For this purpose, I would like to understand better what methods and techniques Rowling uses to make Dumbledore so trustworthy.
Please note that I am looking less for in-world explanations (
"Harry finds Dumbledore comforting (cf. _Stone_ p.142) and overall considers him a father figure, which he's sorely missing") and more for authorial decisions and techniques (
"Dumbledore's ridiculous humor in _Stone_ appeals to the reader, making Dumbledore feel friendly and lovable, and countering the condescending nature of the character").
Specific recommendations for generalizing these observations into my own writing are particularly appreciated.