Imagine this scenario? Would the person feel anything or be injured?
Imagine a bird touched a 100 Exavolt potential line without touching any ground.
  Would the bird ... notice anything when they touched the line ...


Lets make it a sparrow.

No, the sparrow would not notice a thing.
Nor would any observer within a radius of about 10, or 20 or maybe 40 or 50 km.
Outside that radius degree of noticing would be variable and duration of noticing would be varied and the lucky ones may not notice.
Somewhere from around a few 10's of km out an observer would notice, briefly.
Somewhere, beyond many tens of km the observer may live.
(The 1 microsparrow Tsar-Bomba had a total destruction radius of 15 miles.) 

Because:

See references at end for formulae et al

An Exavolt = 10^18 volt or a billion billion volts (US billions). 

Preventing the line arcing to ground will be "an issue" - lets just assume it's high enough. Hanging from balloons maybe.

Self capacitance of an isolated sphere is 4.Pi E0.R
Assume  a sparrow approximates to a 1cm radius sphere. This assumption will be found to be non critical. Capacitance is about 1 pF (1E-12F).
This is an indicator of how much charge a given object can hold.

Let's be conservative and work at 1 Exavolt rather than the 100 suggested.
It will suffice.

Energy transferred to 1 capacitor by a potential change = 0.5 x C x V^2
Here C= 1E-12, V = 1E18
Energy = 0.5 x E-12 x (E18)^2 = 5E23 Joule
1 Terrajoule = E12 joule.
1 Petjoule = E15 joule
1 Megaton =~~ 4 Petajoules.
So sparrow energy = 5E23 / 4E15 ~~= E8 megaton 
Largest H bomb ever = Tsar Bomba  at 50 MT.
So sparrow has more energy than 2 million or so of largest H bomb ever detonated.  

After making allowance for bad assumptions, vague generalisations, specious thinking, general woolliness and lack of coffee, and adjusting everything down generously at all stages, it seems safe to say that your sparrow is toast (and very very very well vaporised toast to boot) AND that living anywhere within about say 100 km of said power line or of said sparrow is liable to be hazardous to your health.

Tsar Bomba = 50 megaton ~= 1 micro-sparrow at 1 Exavolt. 





Related (maybe :-) ):

Capacitance - see self capacitance

Isolated spherical capacitor

Nuclear weapon yield

TNT equivalent

TEV and mosquitoes

LHC &amp; TEV ...

Electrostatics

Mega Giga Tera Peta Exa Zetta Yotta Joule

A bomb energy