D

This corner configuration occurs in 4 of the 27 possible cases (14.8%). There are 7 distinct positions.

Thanks to Bernard Helmstetter for the D4 solution, and to Matthias Hunt for the D2.

Simple sequences
[15.0 average]

1/12
8%

Sune + Sune (= C1)

1/12
8%

AntiSune + Bruno

2/12
17%

Sune + Sune

2/12
17%

AntiSune + Sune

2/12
17%

Bruno + AntiSune

2/12
17%

Sune + Rune

2/12
17%

Sune + AntiSune

Perfect sequences
[13.9 average]

1/12
8%

2/12
17%