Eric and Sookie have had each others' blood (in the books) 9 times to date.

0 times in Dead Until Dark

4 times in Living Dead in Dallas
Pg. 39 Eric --> Sookie
Pg. 169 Eric --> Sookie
Pg. 191 Sookie --> Eric
Pg. 243 Sookie --> Eric

1 time in Club Dead
Pgs. 164-166 Sookie --> Eric

2 times in Dead to the World
Pg. 123 Eric --> Sookie
Pg. 125 Eric --> Sookie

1 time in Dead as a Doornail
Pg. 221 Eric --> Sookie

0 times in Definitely Dead

1 time in All Together Dead
Pg. 178-179 Eric --> Sookie --> Eric

0 times in From Dead to Worse