The Qur'an says that the angels do not disobey God and do as they are commanded (Qur'an 66:6). It is also narrated from Imam 'Ali (A) that the angels do not disobey or tire. From this, we can glean that the angels do not disobey Allah.
Possibly, angels may have the inherently capability to disobey but simply choose not to do so, because they have no reason to do it and no inclination to do it.
This is often understood as being because angels have intellect but no animal desires, unlike human beings, which have both intellect and animals desires, and usually it is either our bodily urges or related traits (such as anger) which cause us to do wrong.
The angels also have a greater awareness of higher realities (such as things pertaining to Allah) as well as the ugliness of some wrong acts, so perhaps this also may contribute to not wishing to do wrong things, unlike people, who are sometimes blind to these things.
For this reason, stories like that of Fotros can be considered questionable.
God knows best!