V, 36 bytes

.1->
uGYVH""pØHi, Retina! üˆ.*±
Ø^0$

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Satisfies:

2. The first character is a ..
3. It contains an e.
4. Its length is even.
5. Its length is a perfect square.
6. It contains an a.
7. It contains a > character.
8. Contains the exact string ->.
9. Contains the exact string Hi, Retina!.
10. The sum of the first two Unicode code points is a multiple of 5.
11. The 10-th character is a ".
12. The last line does not have any duplicate characters.

For future answers:

• The first character is a ..
• Its length is an even perfect square.
• Contains the exact sequence ->.
• Contains the exact string Hi, Retina!.
• The second character's Unicode code point, mod 5, is 4.
• The 10-th character is a ".
• The last line does not have any duplicate characters.