Ive always wondered about this situation:

X = clear terrain
F = Friendly figures
O = Opposing figure
C = Character who wants to attack with close combat

XXXX
XFOX
XCFX
XXXX

And now in this situation:

B = Blocking terrain

XXXX
XFOX
XCBX
XXXX

In the first situation the character (C) wants to attack someone (O) he is right next to, but only on the diagonal. Is he still classed as adjacent and able to attack? In the second example, one of the diagonals is blocking terrain so can he attack?

In these examples, would he be able to draw LOF for outwit through the diagonal of 2 friendlies?

Thanks in advance for helping to clear this up once and for all.

He is adjacent in both examples and can make the close combat attack. (Note that the F's can be friend or foe.)

Nope. There is no LoF through that diagonal. (This even prevents a sharpshooter from making a ranged attack through there.)

Thanks for clearing that up

Although keep in mind that if at least one of the two "F" figures are opposing Sharpshooter would allow the shot.