In Metaphor: ReFantazio, bonds do not always rank up simply by speaking to the followers. The ranking up of bonds is dependent on several factors, including:

1. Automatic Bonds: Some followers form automatic bonds, which do not require any specific actions or choices.
2. Conversation Checks: For bonds that require conversation checks, the protagonist must engage in specific dialogue choices to increase the bond level. The correct dialogue options reward Magla (MAG), which is used to study new Archetypes and inherit moves.
3. Side Quests: Completing side quests is necessary to unlock the next bond event conversation for certain characters. For example, to unlock Junah’s bond, you must complete the side quest “Save the Mourning Snakes” on Virga Island.
4. Virtue Requirements: Some bonds require specific Virtues to be at certain levels. For instance, Heismay’s bond requires Eloquence at level 2 and Imagination at level 4 to rank up.

Therefore, a yellow mark indicating a bond is available for conversation does not automatically mean the bond will rank up. You must ensure you have met the necessary requirements and engage in the appropriate dialogue choices to increase the bond level.