I decided to do a line count of all of the supports in the game by character. I made a spreadsheet that shows how many lines each character has to each other character, but here is the complied data.
Support line count:1. Mercedes von Martritz (BL) – 681 [15 supports]
2. Annette Fantine Dominic (BL) – 669 [15 supports]
3. Hilda Valentine Goneril (GD) – 642 [15 supports]
4. Claude von Riegan (GD) – 634 [14 supports]
5. Lysithea von Ordelia (GD)- 634 [16 supports]
6. Ferdinand von Aegir (BE) – 619 [14 supports]
7. Ingrid Brandl Galatea (BL) – 611 [15 supports]
8. Linhardt von Hevring (BE)– 605 [14 supports]
9. Bernadetta von Varley (BE)– 601 [15 supports]
10. Ashe Ubert (BL) – 600 [14 supports]
11. Lorenz Hellman Gloucester (GD) – 586 [14 supports]
12. Dorothea Arnault (BE) – 585 [14 supports]
13. Sylvain Jose Gautier (BL) – 584 [17 supports]
14. Caspar von Bergliez (BE)- 576 [14 supports]
15. Dimitri Alexandre Blaiddyd (BL) – 575 [14 supports]
16. Leonie Pinelli (GD) – 564 [15 supports]
17. Catherine (CoS) – 563 [13 supports]
18. Ignatz Victor (GD) – 559 [14 supports]
19. Felix Hugo Fraldarius (BL) – 531 [14 supports]
20. Flayn (CoS) – 524 [12 supports]
21. Raphael Kirsten (GD) – 522 [14 supports]
22. Petra Macneary (BE) – 513 [14 supports]
23. Byleth Eisner (CoS) – 505 [35 supports]
24. Seteth (CoS) – 489 [11 supports]
25. Shamir Nevrand (CoS) – 489 [12 supports]
26. Marianne von Edmund (GD) – 487 [14 supports]
27. Manuela Casagranda (CoS) - 479[12 supports]
28. Edelgard von Hresvelg (BE) – 465 [11 supports]
29. Hanneman von Essar (CoS) – 457 [12 supports]
30. Alois Rangeld (CoS) – 414 [11 supports]
31. Hubert von Vestra (BE) – 402 [10 supports]
32. Dedue Molinaro (BL) – 395 [11 supports]
33. Cyril (CoS) – 390 [11 supports]
34. Gilbert Pronislav (CoS) – 281 [9 supports]
35. Jeritza von Hrym (BE) - 102 [2 supports]
36. Rhea (CoS) - 56 [1 support]
Total lines: 18386
*Note: In Lysithea / Cyril and Sylvain / Bernadetta, there are several lines which is one of the characters in the support reading the other character’s letter. I counted those lines toward the speaker, not the writer.
Next is the S supports and the Goddess Tower sequences.