BEGIN AND END IV

The partial words below can be completed by adding the same two letters, in the same order, at both the beginning and at the end:

1. _ _ I _ _
2. _ _ R _ _
3. _ _ TI _ _
4. _ _ IT _ _
5. _ _ CI_ _
6. _ _ ON _ _


HINTS:
The first of the two letters are:
1. O
2. V
3. R
4. E
5. D
6. I

Answers:

1. ONION
2. VERVE
3. RETIRE
4. EDITED
5. DECIDE 
6. ICONIC