Latin root fect means to do, make
The latin root fect appeared in a lot of frequently used English words like affect, infect, etc.
dhe: Proto-Indo-European root meaning "to set, put, place." The Latin verion is facere, you can see the meaning changed a little bit, but still connected, the older meaning shows up in some words such as infect, affect, etc. The dh sound becomes 'f' or 'd' in Latin, the 'd' is understandable, but 'f' is a surpise. This is how it changes: dhe with suffix k, dhek, then dak, we all know that in Roman the k and c are equivalent, it becomes dac, with more inflections we get facere.
The excerpt from book "Wondering about Words: D'où viennent les mots anglais?"
facere: The Latin verb which means to do, to make, to feign. The present active infinitive of facio.This verb expand to a large amount of English words, some of them seems not related but have the same origin.
fect: stem of ficere which is an variation of facere.
All three are variations of facere.
ficere: sometimes the "a" becomes "i", facere becomes ficere. Another example in+amicus becomes inimicus
inficere: immerse in dye, discolor, taint, poison
infectus: past participle of inficere.
From inficere to infectus to infect. Means put into. Physicially, it means to put poison, taint, disease into body to cause a health problem. Mentally it means put an emotion into people's mind to infulence them.
Put influence to something or someone. You can think of affect as trying to infect, when the affect works, it means the target is successfully infected. It's also possible the trying has no effect on the target when the affect failed.