Thanks Alianore, this is all new to me! 
Maybe he indulged Eleanor because she was his first child? 
You're welcome!
I think that's quite likely - Edward III was also very indulgent of his eldest daughter Isabel (b 1332). She didn't marry till she was well into her thirties, about 20 years later than you'd expect!
About bell's questions: I believe Joan of Acre was his favourite sister. She was 12 years older and might have been very maternal, and she never left England. Edward later showed a lot of favour to her eldest daughter Alianore de Clare, long before her husband Despenser became his favourite. His sisters Joan, Elizabeth and Mary (the nun) were all very supportive of him when his father cut off his income after a huge row between them in 1305. (Eleanor was dead by then and Margaret was in Brabant). It seems that the affection was mutual.
About Ed's half-brothers: I'm not really sure if they were that close - there aren't many records showing that he sent them gifts or visited them often, for example. He did pay the messenger who brought news of the elder one's birth a huge sum of money. The age difference was enormous, really, and by the time they were old enough to be useful to him politically around 1320, Despenser was well ensconsed (sp?) in the royal favour, which marginalised them. Don't forget, Kent (the younger one) invaded England in 1326 with Isabella and Mortimer, and Norfolk joined them immediately. (They might have only been trying to topple the Despensers, not their brother, of course, but it was still rebellion against him.) As usual it's impossible to be sure, but my feeling has always been they weren't particularly close.
