Some devils have abodes and as mentioned in Ayah 36 of Surah Al-Zokhruf, Allah (SWT) said: Has infiltrated the soul of the human being, somehow that person is not bothered anymore, Satan is a soulmate at all the times and this is because that person is not righteous. Some other Satans cannot infiltrate but they weaken a believer as mentioned in Ayah 201 of Surah Al-Aaraaf: Satan cannot infiltrate but can shake them; they realise this and seek refuge in Allah (SWT). There are human beings who are worse than Satan as mentioned in the Quran; therefore it is possible for a human to be a devil. Whoever does act like a devil, to encourage selfishness or praising others without justification is evil. Ayah 176 of Surah Ale-Imran said: Those who are hasty in their disbelief and join this and that, do not worry about them, they cannot harm you.
(Explanations by: Hojjatul Islam Qara’ati)