Ahead of facing off against each other in the FA Cup quarter-final on March 11, the Royals boss has detailed the circumstances that brought him to the club, and the role of then-manager Alan Pardew. Now in charge of Palace, the 54-year-old has seen his Reading legacy go from strength to strength on the pitch, even if his own reputation with the fans is in tatters.
"I was managing Woking in the Conference," McDermott told The League Paper.
"I went to a reserve game at Brentford and Alan was there. He was in charge at Reading.
"I didn’t know him at all, but we got chatting, got along well and kept in touch. I lost my job at Woking and, a few days later, the phone rang.
"It was Alan, asking if I’d be his chief scout. Obviously I said yes.
"I was quite young and I’d never done that before, so it was an interesting few years, to say the least. But, before long, Alan had me doing the Under-17s as well, so he certainly got his money’s worth!"
The Friday night fixture, live on BBC One, represents Reading's fourth quarter-final in seven years, whereas the Eagles haven't reached this stage of the competition since 1995.
"I'll always be grateful to Alan for bringing me here and he's still a very good friend of mine."
"He's a fabulous manager. Just look at what he's done. Promotion with Reading. He got West Ham into the Premier League and to an FA Cup final.
"He did a great job under difficult circumstances at Newcastle. He's galvanised Crystal Palace this season.
"He's highly-rated in the game, that's for sure. Everybody knows his ability and he's never been out of work for long, has he? I'll look forward to seeing him."
In the match, the Royals are likely to call upon the services of academy stars such as Hal Robson-Kanu and Jake Cooper, and McDermott is well aware of the strength of his club's youth system.
"I think it is important. Your academy is your lifeblood, and Eamonn [Dolan] has done such an incredible job.
"These days, it's so hard to break through at the top clubs. The top four or five have the best international players. There's no pathway.
"Here, there is. If I had a son with a bit of ability, I'd want him to be at Reading."
Looking ahead, it is clear the Royals manager is keen to create more stars of the game, to follow in the footsteps of Shane Long and Gylfi Sigurdsson.
"Shane Long’s a good friend of mine,"
"I go to see him regularly and we’ll often have dinner. I enjoy seeing what he’s done. Gylfi is another one who we brought through. Both of them will hopefully be playing at the Euros this summer. That means a lot."