DL and VS. Time To Ask Where This Relationship Is Going?
 

So what is going on between DL and VS? VS isn't a Skyteam member but they seem to be more than your average codeshare partner. Why are these two airlines in such a strange relationship? For example, I can book VS through DL on ATL-LHR but I can't book the nonstop VS MCO-LGW flight. It's all very weird. Does VS think they are too good for Skyteam?

DL owns 49% of VS, so no, they're not an average codeshare partner.

Do a little research. DL owns 49% of VS. VS isn't in Skyteam mainly because AF/KLM doesn't find they need them to be. There was a time that they were looking to bring VS into the ST fold but that doesn't look like it'll happen. Doing so would likely require DL/VS JV to become part of the overall AF/KLM JV. Not sure VS is willing to do that. Remember VS still is owned 51% by UK holders. In fact they still do codeshares with Singapore Airlines. Also There's little that VS would bring to Skyteam since it doesn't even operate intra-UK much less EU routes. Basically it's all UK/US. The few other countries all have AF/KLM service.

I would just like an explanation about flight cooperation. There seems to be no rhyme or reason to it. How come I can book MCO-MAN nonstop on delta.com but I can't book MCO-LGW nonstop?

I just tried searching for MCO-LGW on delta.com and got results. Example dates I used were April 21st out and April 28th return.

Interesting. I had tried several dates in February and got the "we don't serve this route..." message. Maybe something is changing in the contract with DL/Vs in the spring.

As to why some routes might/might not be codeshared, I would guess that has to do with antitrust immunity and/or profitability.