SEED factor (Superior Evolutionary Element Destined-factor) is a controversial and as yet unproven theory about the continuation of human evolution. Both Coordinators and Naturals can possess "the SEED," and those who do are thought by some to be the next stage of human development. This bears some similarity to the Newtype theory of the Universal Century, but the abilities of those with SEED factor appear to be unrelated to Newtype potential. While acceptance of SEED theory is limited, Orb engineer Erica Simmons and prominent religious leader and peace activist Reverend Malchio are known adherents of the theory.
SEED mode represents the ability for an individual with the SEED factor to enter into a state of enhanced awareness and peak physical ability. While in this state, the person (usually a mobile suit pilot, but not necessarily) demonstrates heightened reflexes and extremely quick information processing. This ability is usually triggered by extreme situations or from recalling significant traumas, often arising out of a need to protect someone else in a critical situation.
According to an interview with the producer on the official guide book, the producer claims that the SEED mode is like people having superhuman strength during an outbreak of fire and can carry extremely heavy weight out of the fire scene but can never even dream of carrying in normal daily life.
First-stage Extended humans possessed strong enough combat abilities to press even very strong Coordinators such as Kira Yamato or Athrun Zala. However, second-stage Extended humans proved to be somewhat weaker than their predecessors; evidence of this is the fact that they could not hold their own vs characters in SEED mode, while the first-stage Extendeds did. However, the second-stage Extendeds appear to be much more mentally stable than the first-stage Extendeds and have been intended to be more "useful"; Sting, Auel, and Stella demonstrated that they were not only fair pilots, but also capable of blending into a crowd and acting (at least somewhat) like normal teenagers, capable of taking orders from superiors better, capable of man-to-man combat on an excellent level, and easier to control than first-stage Extendeds. Extended humans could be considered analogous to the Universal Century concept of "Artificial" or "Cyber-Newtypes", who were normal pilots enhanced to have Newtype abilities.
Kira Yamato and Cagalli Yula Athha originally entered SEED mode via the first method, though Kira attained the ability to use the second method shortly after he was beaten by Athrun, once he had received the ZGMF-X10A Freedom and had decided what it was he needed to fight for.
In the Second Battle of Jachin Due during the first war, Lacus Clyne may have entered SEED mode after a long philosophical soliloquy about the nature of warfare and death. During the Battle of Messiah in the second war, Lacus sensed Kira and was in SEED mode yet again.
Shinn Asuka, the only new pilot in Mobile Suit Gundam SEED Destiny to achieve the SEED mode, always uses the first method in response to his rage over the events of the battle he is in at the time. The first way of entering SEED mode changes in Gundam SEED Destiny. When Shinn enters SEED mode it is shown that the SEED explodes (with more color) and zooms out from the eye.
SEED mode can only be entered by characters who can commit themselves fully to a battle for some strong reason. For this reason, Athrun Zala and Cagalli have both been unable to demonstrate their SEED abilities in earlier parts of Gundam SEED Destiny, due to Athrun's doubts about whether ZAFT is really justified to fight this war and Cagalli's reservations about whether her interventionism is the best way to protect Orb from the war. Kira, however, has been able to activate his SEED mode at will all throughout Gundam SEED Destiny, because he is motivated to protect his friends (and indeed, the entire world) from aggressive powers.
Some fans who are new to the SEED universe think that only Coordinators have SEED abilities, which often leads them to wonder if Cagalli Yula Athha is actually a Coordinator. The explanation for this common mistake is that the writers have a preference for Coordinators and similar individuals; this is also the reason why almost every important pilot in the series is either a Coordinator or an Extended. Hence, Cagalli is apparently the only Natural pilot with SEED abilities. Cagalli's genetic type is never fully explored in the first place. While Uzumi Nara Athha clearly states that she is a Natural and it would appear in the flashbacks that her biological mother is pregnant with her (indicating she was to be born without genetic enhancements, whereas Kira developed in an artificial womb), it is possible that, since she is Kira's twin, she may have undergone some genetic enhancement, though this is highly unlikely.
