The Bitterness Trilogy/Heartwarming

The Bitterness of Phineas Flynn:

Pretty much the entity of Chapter 5 combines this with Tear Jerker, but this moment takes the cake:

"Do your best," said Ferb. "And you need not forget me. It is good to remember the blessings of our past. You must try to put the bad things behind you, but never forget what you learned from them." Phineas looked at Ferb with pain, sorrow, and fear evident on his face. Ferb, despite the fact that he was a spirit, embraced his brother. Phineas wasn't sure how this was possible, but didn't really care. He hugged his beloved brother back.

Phineas's love confession to Isabella.
When Ferb is resurrected and the brothers are tearfully reunited.
- The scene was recently edited, so it's now ten times as touching.

"I thought I lost you forever..."

The Bitterness of Candace Flynn:

When Phineas hits a Despair Event Horizon after discovering Candace has become evil and begins to cry, Ferb comforts him and some extremely sweet dialogue is shared between the two.

Ferb: As your brother, I'll always be here for you.

"Just...remember...no matter what...we'll always...love...you..."
The entity of Chapter 4. Yes, the entire thing.
- Highlights include:
  - The visions the boys get of Phineas's deceased biological father.
  - "We still love you, Sis. No matter what, we always will."
  - Candace's Heel Face Turn.
  - Candace cradling Phineas in her arms until he wakes up.
  - The hug they share in the same paragraph.
  - Then, later, the Group Hug shared by all the siblings.