- "He can see the relationships or connections people have to one another. For example, in a group situation he can easily pick out the leader, or sense the strength of the bond between mates or friends. He can also see where those bonds are weak."
- ―Entry on Marcus's gift[src]
Marcus uses this ability to sense the relationships of those around him, along with the intensity of the ties that bind them, allowing him to see who would die for another or turn traitor, given incentive. He also uses it to sense how someone feels about the Volturi if they refuse physical contact with Aro. He can identify lovers, friends, family, etc. through this power; and can also detect several different emotional links at the same time.
When utilizing this skill in a battlefield, Marcus is quite dangerous, as he can identify both the strong and weak links of the enemy ranks, potentially ending the battle in the most efficient way possible.
- "Marcus's gift is actually quite valuable in the hands of someone who knows how to use it. For example, imagine Marcus on the battle field. He sees the binding ties between the enemy the guard faces. He can tell who the leader is just by watching the way the others are tied to him/her. He can see how to destroy the resistance simply by picking off a few key people. He doesn't just see romantic relationships, but also ties of family and friends, loyalty and devotion. He can tell if any given person would die for another. Off the field of battle (as the Volturi rarely leave their home), Marcus's gift is valuable politically (for lack of a better word). It's an amazing gift in a diplomatic situation. Plus, when you're sitting on an empire, it's nice to be able to see when someone's loyalty starts wavering. Or if anyone is getting too fond of anyone else. Can you see the potential now? Marcus didn't get where he is with some fluff skill."
- ―Stephenie Meyer's description of Marcus's gift.
Aro found Marcus's power useful in detecting the emotional bonds of their enemies and how to use those bonds to their advantage. His power was so useful to the coven that Aro sacrificed his own sister to keep Marcus from leaving.
- "Marcus sees relationships. He's surprised by the intensity of ours."
- ―Edward, on Marcus's power.[src]
In Breaking Dawn, Marcus uses his power to detect the bonds between the Cullens' allies and shares his information with Aro.
- Eleazar can identify the type and strength of another individual's gift in his presence, similarly to how Marcus can sense the strength of emotional bonds.