Can anybody crack the enigma code that is Charlie Zog?
He was part of the Sir Bobby Robson legacy at St James' Park but he left Tyneside under a cloud during the ill-fated Joe Kinnear era.
That sentence alone makes it easier to understand why Charles N'Zogbia ended up being disillusioned in Toonland.
Kicking players up the backside, burning their clothes and feeding them on egg and chips in the style of Wimbledon was never going to work with some players - not least Zoggy!
And calling him Insomnia in front of a packed Press conference was like showing a red rag to a bull.
But what is it with the Zog?
On the one hand you have a player blessed with pace, skill, creativity and an eye to score blockbusting goals.
On the other hand you have a player that turns up when he wants to, has mood swings and tantrums and has been known to cause the odd blow out on the training field.
Whatever way you look at it, it's down to both management of the individual and his own attitude.
Then you have the "never go back" argument.
Not too often in football does a player enjoy the same success the second time around as he did the first.
For Zoggy, if Newcastle can win the race for his signature, it may well be more a case of unfinished business.
In Alan Pardew and John Carver you have a combination of experienced management figureheads who can coax good performances out of individuals if they are given the time to work on it.
So far they've had only four months and it could be argued that finishing in the top 10 or top eight is a platform to build on.
Either way the return of the Zog could make for interesting times ahead if United can pull the transfer off.